1H THE NATURAL HISTORY [LETT. 



six weeks in autumn it hardly eats at all. Milky plants, such 

 as lettuces, dandelions, sowthistles, are its favourite dish. In 

 a neighbouring village one was kept till by tradition it was 

 supposed to be a hundred years old. An instance of vast 

 longevity in such a poor reptile ! 



RINGMER, near LEWES, Oct. 8, 1770. 



LETTER XXXIX. 



TO THOMAS PENNANT, ESQ. 



AFTER an ineffectual search in Linnasus and Brisson, I begin to 

 suspect that I discern my brother's Hirundo hyberna in Scopoli's 

 new discovered Hirundo rupestris. His description of " Supra 

 murina, subtus albida ; rectrices macula ovali alba in latere 

 interno ; pedes nudi, nigri ; rostrum nigrum ; remiges obscuriores 

 quam plumaB dorsales ; rectrices remigibus concolores, cauda 

 emarginata, nee forcipata ; " l agrees very well with the bird 

 in question ; but when he comes to advance that it is " statura 

 hirimdinis urbicse," and that " the definition given of the bank- 

 martin suits this bird also," " definitio hirundinis ripariae Lin- 

 nsei huic quoque convenit," he in some measure invalidates all 

 he has said ; at least he shows at once that he compares them 

 to these species merely from memory : for I have compared the 

 birds themselves, and find they differ widely in every circum- 

 stance of shape, size, and colour. However, as you will have 

 a specimen, I shall be glad to hear what your judgment is in 

 the matter. 



Whether my brother is forestalled in his nondescript or not, 

 he will have the credit of first discovering that they spend their 

 winters under the warm and sheltery shores of Gibraltar and 

 Barbary. 



1 " Above it is mouse-colour, below whitish, the guiding feathers with an 

 oval white spot on the inner side, the feet bare and black, the beak black, 

 the wing feathers darker than the dorsal ones, the guiders of the same colour 

 as the wings, the tail well defined, not forked." 



